Uplink data transmission for high speed trains in severe doubly selective channels of 6G communication systems

This paper proposes a transmitter–receiver architecture for the transmission and detection of data from high-speed-trains (HSTs) to base-stations (BSs) in sixth-generation (6G) communication systems. The scenario that is considered in this paper assumes that each HST passenger-car (PC) transmits data to its closest BS and therefore, several PCs communicate with the same BS simultaneously. The projected transmitter–receiver architecture employs a new Doppler-shift-frequency (DSF) estimation method, proposed in this article, to estimate channel taps’ DSFs. Using these estimated DSFs, the channel taps’ angle-of-departures (AoDs) are calculated. Each PC beamformer uses these AoDs to adjust its coefficients to suppress interference-channel-taps (ICTs) and to direct its beam towards its line-of-sight-channel-tap (LoSCT). Afterwards, a DSF compensation block is used to mitigate the LoSCT’s DSF. The proposed DSF estimation scheme is a finger print based approach which includes an offline training phase, and two real time phases. The estimated optimized receiver coefficients in the offline training phase and the estimated channel parameters in the first real time phase are used to obtain an accurate estimate of the LoSCT’s DSF in the second real time phase. Simulation results designate the reliability of the proposed DSF estimation scheme and the proposed transmitter–receiver architecture.